What happens with drag and students?

During my standing here, I have seen a lot of repetitive threads. But the most recurrent question of every students who post here is about air resistance and drag coefficient. What happens with it?. Is there any hidden mystery we could not see?. This fact is starting to be very unusual and curious. It seems like professors at school don't explain the stuff very well.

I would think that one reason is that when students start with classical mechanics of particles and rigid bodies, they get so used to the idea that kinetic friction is proportional to normal forces that they start to think of all resistive/dissipative forces in this manner. That is, when they encounter air resistance, they think it as weird and diffucult to understand that a resistive force doesn't follow the scheme they are used to.